Night Feeding by Guppies Under Predator Release: Effects on Growth and Daytime Courtship

Abstract

The nonlethal effects of predation threat can be pervasive but are also easily overlooked. We investigated effects of predation threat on feeding by guppies (Poecilia reticulata), and how threat-induced temporal shifts in feeding activity affect reproductive behavior and growth. Contrary to the view of the guppy as a ''diurnal'' species, our observations revealed that guppies free from severe predation threat expand their foraging into the nocturnal period. We found such nocturnal foraging to be as profitable as diurnal foraging, and guppies under threat incurred a substantial growth penalty when predators inhibited night feeding. Denial of night feeding also decreased daytime courtship by males, facultatively duplicating a classical observation comparing courtship intensity in contrasting predator regimes, but providing a novel mechanism for the effect. Our findings support the view that evaluations of predator effects on life histories should consider potential predatorcaused alterations in size-specific energetic gain, along with the classical consideration of predator-altered mortality rates. The results of this study show that predation threat can induce a large, facultative shift in the temporal niche and vital rates of a prey species. We discuss some implications of the effect in the broader contexts of predator facilitation, evolution of life histories, and trait-dependent decisions to boost daily intake by expanded feeding times.

Environmental and genetic influences on mating strategies along a replicated food availability gradient in guppies (Poecilia reticulata)

“…Fraser et al (2004) found that denying male guppies the opportunity to feed at night reduced their diurnal courtship activity (time spent following females) and suggested that release from predation allows males to forage more at night and thereby court more during the day. Although these authors did not examine male-male interactions or court ship displays, their results suggest that costly mating activity is limited by food intake.…”

Sensory constraints in temporal segregation in two species of anglerfish, Lophius budegassa and L. piscatorius

“…In fact, tagged and recaptured L. piscatorius demonstrated in-and offshore movements in the northeastern Atlantic , Therefore, these species may rhythmically swim between the shelf and the slope, with the main part of the population moving into shallow water areas during 2 opposite times in the day-night cycle. Although prey species are known to shift their activity patterns to avoid predation (Fenn & Macdonald 1995, Fraser et al 2004, it is also common to observe a similar phenomenon among predators that compete for the same prey (Schoener 1986, Soria-Barreto & Rodiles-Hernández 2008. While this competition is reduced for species of mixed predatory and scavenging activity, pressure is likely to be stronger for more specialised piscivores such as anglerfish.…”

The effects of different predator species on antipredator behavior in the Trinidadian guppy, Poecilia reticulata

“…We had also expected this because acaras are also diurnal, pursuit predators, but are less piscivorous, having more omnivorous diets commonly associated with disciform fish (Merigoux and Ponton 1998). Wolf fish, however, are highly piscivorous and were shown to greatly affect the behavioral time budgets of guppies (e.g., Fraser and Gilliam 1987;Fraser et al 2004). Despite this, guppies did not significantly reduce foraging time or increase time spent in the surface water in the presence of a wolf fish compared to the control, and the mean shoal size of guppies was lowest in the wolf fish treatment.…”

“…However, their effect on populations of Hart's rivulus, Rivulus hartii, another small fish sympatric with guppies, was well documented (e.g., Fraser et al 1999;Gilliam and Fraser 2001) and because juveniles sometimes hunt in daylight (M. S. Botham et al, personal observation) and feed both diurnally and nocturnally in the laboratory (Botham and Krause 2005b), they should be considered in studies relating guppy evolution to predator faunas. For example, nocturnal predation by wolf fish causes guppies to reduce their courtship during the day to compensate for lost feeding opportunities during the night (Fraser et al 2004). In a field study investigating the effects of shoaling behavior on prey choice, shoals of guppies were attacked frequently by all three of these predator species .…”